What's the difference between a fiberglass and an organic shingle? The difference between a fiberglass and an organic shingle is the type of mat that is used. Organic mats, which are used to make organic asphalt shingles, are composed primarily of cellulose fibers derived from selected recycled paper or converted wood chips. On the other hand, the mats used to make fiberglass asphalt shingles are composed of glass filaments of various lengths and orientations, bonded together with inert binders. In most climates, both shingles, if installed properly on well-made roof decks, perform similarly. See CASMA Technical Bulletin No. 20 for more information.

Why/when should I use an asphalt shingle underlayment? An asphalt shingle underlayment is typically dry felt that may be impregnated or coated with an asphalt saturant. The use of an underlayment is recommended for the following reasons:

Resins are produced by wood board decking. Asphalt-saturated felt protects shingles from the resins that may be released.

Can I apply new shingles over existing shingles? That depends on the condition of the roof. If the roof has one layer of shingles that are lying flat and the deck is in good condition, the existing shingles typically do not have to be removed. Check with local officials to make sure that building codes are being followed. Reroofing is also a perfect time to examine roof ventilation to ensure vents are unobstructed, properly positioned, and sufficient in number.

What offsets should be used for laminated shingles? For laminated shingles, the recommended offset is 10 inches. Typically, laminated shingle offsets range from 6 to 10 inches. Regardless of the shingle type, it is always best to follow all application instructions printed on the shingle package. This will ensure proper roof performance and finished roof aesthetics. Laminated shingles must be applied with a minimum offset no less than 4 inches.

How can I ensure proper performance from shingles in cold climates? Proper performance from shingles installed and used in cold weather can be achieved by following the recommendations listed below:

Make sure that the roof is properly ventilated.

Be careful when using shingles in cold weather. They tend to get brittle and may crack or break. Take care not to throw, drop, or bend shingles.

If you are in an area that experiences freezing winter temperatures, eaves protection should be used to reduce water damage from ice dam formation. Use self-adhering eave protector membranes. They are easier to work with in cold weather.

Hand-seal asphalt shingles in cold weather with an asphaltic cement recommended by the manufacturer.

When applying ridge caps, keep the shingles that are being used for this purpose in a warm place so that they will be flexible enough to bend.

When recovering an existing roof with new shingles, make sure that the old shingles are flat.

In areas that receive high amounts of snowfall, try not to damage shingles when removing snow. Damage caused by snow removal is not covered under our limited material warranty.

Use caution if walking on a roof in the wintertime. The sealant bond between shingles can become quite brittle in cold weather. Therefore, traffic on the roof may cause sealant bonds to break.

Which type of fastener should be used to install asphalt shingles-nails or staples? We agree with and support the ARMA position that nails are the preferred method of fastening asphalt shingles due to their superior holding strength. The following fastening tips apply to most composite shingles:

A minimum of four fasteners per shingle are used.

Correctly place and position fasteners below the sealant strip, but above the cutout on three-tab shingles, and in the nail line on laminated shingles.

The fasteners must be straight and flush with the surface of the shingle, not sunk into the shingle or sticking up at any point.

Make sure there is correct penetration of the deck as specified by ARMA and the NRCA.

Do I need to peel the release tape off the shingles? The plastic release film on the back of composite shingles does not need to be removed. The sole purpose of this tape is to prevent the shingles from sticking together in the package. Once the shingles have been removed from the package and are applied in the correct orientation on the roof, the release tape serves no purpose whatsoever. The shingle sealant, which bonds the shingles together, is located elsewhere on the shingle and will seal succeeding courses of the shingles together on the roof when warmed by the heat of the sun, soon after application.

What is causing the algae growth on my shingles? Algae growth is typically seen on light-colored shingles. It exists as a brown to black discoloration of the shingle and is caused by an algae known as Gloeocapsa. Although its presence may be aesthetically undesirable, it does not affect the performance of the shingle.

How do I get rid of the algae growth on my shingles? There are several ways to reduce the discoloration caused by algae:

For a new roof, install a zinc or galvanized-type metal near the ridge of the roof. As the metal ions are oxidized and erode off of the metal strip, they wash down the roof, inhibiting cellular algae growth.

A dilute solution of chlorine bleach, trisodium phosphate (available at paint supply stores), and water can be applied-one part chlorine bleach to three parts water with a quarter cup of trisodium phosphate. Gently spray the solution on the shingles, being careful to avoid damaging other parts of the building or the shrubbery below. For stains that are hard to remove, scrub mildly, as scrubbing too harshly will remove granules. Rinse the shingles thoroughly with water. This process usually needs to be repeated every couple of years.

Due to the increase in algae-discolored roofs, shingles are now available with small quantities of zinc or copper granules embedded in the mineral surfaced granule coating. These particles inhibit the algae growth through some of the life of the asphalt roof.

Can bird excrement affect asphalt roofing products? A buildup of bird excrement on asphalt roofing products can have negative effects if it remains on the product for a considerable amount of time. In some instances, it can even shorten the life of the product. Companies specializing in bird control offer several ways to minimize this problem.

Can hail affect asphalt roofing shingles? Yes. Hail can cause both aesthetic and functional damage to asphalt roofing shingles. Aesthetic damage is characterized by a slight granule loss, while functional damage is defined by substantial granule loss or cracking or penetration of the shingle. Functional damage may result in short-term leaks or a reduction of the life expectancy of the shingle. According to CASMA Technical Bulletin No. 14 (1997), several factors affect how roofing shingles will perform in hail:

Age of the shingles-newer shingles are more resistant than older shingles, as the asphalt is less brittle and better able to absorb the impact energy.

Angle of hail impact-hail that strikes the roof at a 90-degree angle is more likely to cause shingle fractures, while hail that strikes the roof obliquely is more likely to result in spots of granule loss.

Temperature-fractures are more likely in cold weather as the asphalt becomes more brittle than in warmer weather.

Roof deck conditions-solid roof decks on moderately spaced trusses offer better support to the shingle surface in resisting hail damage. Shingles on rotted or flimsy decking can be more easily fractured.

What is buckling? Buckling is defined as ridges that form along the length of the shingle, with the ridge spacing usually coincidental with deck board joints. These ridges are caused by the shingle being distorted from the movement of the deck. Buckling can occur with any deck type, but is more common with board decks, and less common on plywood decks. Buckling can occur when a new roof is installed, even if the old roof did not show any buckles. When the roof is stripped, the deck may be exposed to moisture, causing dimensional changes in the supporting lumber.

Should I be concerned about small bubbles/blisters on my shingles? No. Practically all asphalt shingles have, by the nature of their manufacture, a greater or lesser degree of blistering potential under certain conditions or combinations of conditions. Generally, blistering is difficult to see from ground level and does not necessarily shorten the life of the shingle.

What is color shading? A roof observed from different lighting conditions or angles may have darker or lighter spots in certain areas. This apparent difference in color is referred to as "shading." Shading is usually caused by unavoidable slight variations in texture that occur during the manufacturing process. Black or dark-colored shingles are more prone to shading problems. A small amount of light is reflected from dark surfaces. Therefore, even slight textural differences may cause shading. Light-colored shingles reflect greater amounts of light than darker shingles, making shading problems less noticeable. Since blends are made from a number of colors, shading differences are masked and are even less noticeable. Additionally, the material on the back of a shingle is sometimes transferred to other shingles that are next to it. And when shingles are stacked too high or stored for long periods of time, stains can develop. Both conditions can create the appearance of shading. These are only temporary problems and the will naturally weather off. Shading does not affect the watershedding performance or life expectancy of a shingle.

My gutter is filled with granules. Is there a problem with my shingles? Not necessarily. Excessive amounts of granules are applied during the shingle manufacturing process to make sure that the asphalt on the roofing sheet is completely covered. It is important to completely cover the sheet with granules so that the asphalt is not exposed to ultraviolet light. The granules are then pressed in. Due to the excessive amount of granules applied, some of the granules are only held loosely in place. Most of the excess granules are removed by the shingle manufacturing process, but some of these granules do get packaged with the shingles. These excess granules are known as "hitchhiker" granules. These hitchhikers will typically come off during the first two years of shingle exposure on the roof. They usually will be found in gutters or at the bottom of downspouts. The loss of these granules is normal and does not affect the performance of the shingle. Granule loss only becomes a problem when the asphalt becomes exposed on the surface of the shingle.

What is fishmouthing? Fishmouthing is the raising of a portion of the front edge of a shingle to create an "eyebrow" appearance. This may occur at the lower tab edge or along the cutout edge. These distortions may be more noticeable on certain roofs because of the slope, sunlight, and shingle color. These fishmouths do not affect the life expectancy of the shingle, and they do not result in leakage, blow-off, or other shingle problems.

What is a splice? Large rolls of organic felt or glass mat are used in the shingle manufacturing process, and a splice is a glued or taped lap of the end of one roll to the beginning of the succeeding roll. Rolls of dry felt or glass mat must be spliced together to maintain continuous shingle production. Each splice is marked for rejection before the shingles are packaged. Occasionally, an error or oversight occurs where that splice gets packaged along with the shingles. Shingles containing a splice will delaminate on the roof within a few months, and should be replaced.

What is winter curling? When the front edge of a shingle tab lifts to form a shallow "U" saucer shape in cold weather and flattens when the weather is warmer, this phenomenon is known as winter curling. Sometimes, the entire front edge of a shingle may lift uniformly. When the top surface of the shingle is cooled, this part of the shingle contracts. At the same time, the bottom of the shingle receives a certain amount of heat from the attic, especially if the attic ventilation is insufficient. As a result, the shingle curls slightly. The appearance of winter curling depend on factors such as the age of the shingle, the type of shingle, roof pitch, attic ventilation, humidity, and climate. Complete elimination of winter curling is rare, although the durability and watershedding properties are not affected.

What is a drip edge and how is it applied? Drip edges are used for watershedding at the eaves and rakes and for preventing wood materials from rotting. It is important that the drip edge is "made of a corrosive-resistant material that extends approximately 3 inches back from the roof edges and bends downward over them." (Residential Asphalt Roofing Manual, 1997) The drip edge should be applied beneath the underlayment or eave protection along the eaves and over the underlayment on the rakes.

What are low-slope roofs? Roofs that have slopes of 4:12 or less are considered to be low-slope roofs. (4:12 means a vertical rise of 4 inches for every 12-inch horizontal run, or 18.4 degrees). Never apply asphalt shingles to slopes that are below 2:12 (9.5 degrees). Shingles applied on low-slope slopes do not last as long as shingles on steeper roof pitches, due to the increased exposure to sunlight and other weather conditions. Generally, laminated/architectural shingles are better suited to steep roofs, and do not offer aesthetic benefits when applied on low slopes.

How can I reduce some of the problems associated with low-slope roofs? Low-slope roofs are more susceptible to water entry due to ice dams and wind-driven rain. Therefore, the key to a successful low-slope roof is to increase the watershedding properties of the roof system. Rain and melting snow do not run off quickly on low-slope roofs. As a result, the potential for ice dams is increased. By providing adequate ventilation, the formation of ice dams can be decreased. "The National Building Code of Canada allows various types of ice dam membranes to be used, but CASMA recommends that self-adhering modified asphalt membranes be used." (CASMA Technical Bulletin No. 16, 1998) Wind-driven rain is another concern associated with low-slope roofs. By improving the underlayment or by using a special shingle application method, the damage caused by wind-driven rain can be reduced.

How many shingles will I need for my project? By using simple calculations, you can estimate the number of shingles that will be needed to complete the job. Roofs come in many shapes and sizes and can be classified into simple geometric shapes such as squares, rectangles, trapezoids, and triangles. To determine how many shingles will be needed, you must first calculate the area of the roof. This is done by figuring out what geometric shapes make up your roof, calculating the area of the individual shapes, and summing the areas to give you the total area of the roof. The area required is then divided by the area each bundle covers. Don't forget to add allowances for ridges, starter strips, etc.

How much ventilation do I need on my roof? The amount of ventilation needed is determined by the size and design of the roof. For roof and attic spaces above an insulated ceiling, the vent ratio is one square foot of not-free ventilating area/300 square feet. For low-slope roofs or roofs with cathedral ceilings, the vent ratio is one square foot/150 square feet.

Can I paint my roof? Yes, the effect of paint on shingles if very negligible. Technically, it could be argued that the paint will help the shingles weather longer. Some roof coatings that are advertised to extend product life are simply premium-quality latex paints.

Do I have to use a certain type of paint on my roof? Yes. Latex paints must be used. Latex paints will do nothing more than color the shingles. On the other hand, oil-based paints may soften the shingles slightly due to the solvents that they contain. These solvents will evaporate quickly, so if used carefully, there should not be any lasting effects. Generally, regardless of the paint that is used, it will weather off within five years. How long the paint lasts depends on the quality of the paint, the pitch of the roof, climate, etc.

How are composite shingles made? Shingles are made in a continuous web process. Large rolls of felt are fed into a dry looper, which serves as an accumulator. The felt then goes to a saturator tank. In the saturator tank, the felt is impregnated with saturant asphalt. From the saturator tank, the felt moves to the wet looper, where the saturant is drawn into the felt as it cools. This allows the felt to attain a high degree of saturation and dries the surface of the sheet. The saturated organic felt or the glass mat (glass mat shingles do not require the saturation process) moves to the coater. At the coater, coating (asphalt with air blown through it) is applied to the top and bottom surfaces of the sheet. Mineral stabilizers are added to the coating to improve the shingle's fire resistance and weatherability. Next, granules are applied to the top surface of coating. Granules are ceramically colored crushed rock; the granules give the shingle its color, but more importantly protect the coating from ultraviolet light. Backsurfacing is then applied to the sheet to prevent it from sticking to the machine and to other shingles when packaged. The release tape is also applied to the back of the sheet to prevent the sealant buttons from sticking to the next shingle in the package. The granules are then pressed into the topcoating. Once the sheet is cooled, sealant buttons are applied. The sealant buttons allow one shingle to bond to the overlying shingle on a roof, to prevent wind uplift. The roofing sheet is then measured and cut into shingles. At this stage, the two pieces of laminated material are adhered together. The shingles are wrapped into bundles and stored in the warehouse until they are ready to be shipped to the appropriate location.

What are ice dams? Ice dam formation is the result of continuous freezing and thawing of snow due to escaping heat from the house or from gutters being backed up with frozen slush. When this occurs, water may be driven under the roof, which may cause ceiling, wall, insulation, and gutter damage.